The present invention relates to apparatus for converting a single wheel mount of a vehicle to a dual wheel mount configuration. The present invention is particularly useful for converting wheel mounts of vehicles which normally have a single wheel attached thereto into dual wheel configurations. It is anticipated that the present invention will be particularly useful for pickup trucks, vans, motor homes, campers, transports, stock haulers, fifth-wheel trailers, tow trucks, tractors and the like.
The vast majority of the contemporary motor vehicles are manufactured so that the axles have wheel mounts to which can be attached single tire mounting rims. For many applications, such wheel mounting arrangements are generally satisfactory. However, there are many occasions when dual wheel mounting at the ends of each axle is highly desirable, especially with respect to the rear or powered axles. For instance, although pickup trucks, vans, passenger vehicles and the like are structurally designed to accommodate certain maximum loads, heavy usage of such vehicles at about their maximum load design places excessive stress upon the vehicle tires. There are also many ocassions when vehicle traction requires augmentation which can be effected most conveniently through additional tire engagement with the surfaces over which the vehicle must travel. One prior art solution is to resort to wider, heavier constructed tires but this solution is not always most desirable especially since it still requires acceptance of the single wheel mount in contrast to the safety factor associated with utilizing dual wheel mounts. That is, a blow-out or deflation of one tire on a dual mount is generally not sufficient to incapacitate the vehicle but is a hazard for any single wheel mount.
Accordingly there has been considerable attention directed toward providing additional wheel mounting for normally single wheel mounting vehicles. It has been suggested that an additional wheel can be attached to the existing axle by incorporating a spacer adapter which can be attached at one end to the axle hub through the existing mounting stud bolts and which has mounting accommodations for the additional wheel at the other end thereof. One example is the double flanged cylindrical adaptor shown by Clark U.S. Pat. No. 3,039,825 with Donnell U.S. Pat. No. 3,837,708 showing yet another version particularly adapted to tractor axles. The use of extended mounting stud bolts along with a spacer type of torsion bar plate is shown in Barr'e U.S. Pat. No. 3,664,709. Barr'e also suggests including extension skirts for the existing fender system so as to ensure coverage of the added dual wheel.
It has likewise been suggested that identical wheel mounting rims be employed so that they can be attached to the common mounting studs on the axle of the vehicle in a back-to-back relation as in U.S. Pat. No. 2,844,409 by Eksergian and also in U.S. Pat. No. 2,545,130 by Ash. However, mounting configurations as suggested by Eksergian and Ash are not well suited for many vehicular applications since the wheel well spacing between the interior surface thereof and the axle mounting hub is insufficient to accommodate such extended mounting hubs as taught by these patents. Thus the vehicle must be originally constructed with exceptional wheel well clearance or the entire wheel mounting associated with the axle hub must be somehow extended. It should also be noted that modifications to inside fender wells to allow for standard dual wheels is not practical for individuals who mount campers in the boxes of pick-up trucks. The width (approximately 40") of the camper will not allow the inside fender wells to be moved inward.
Therefore there has been a continuing need for apparatus which can permit conversion of existing motor vehicles from single to dual wheel configurations without requiring substantial modification to the vehicle structure and further without requiring special design of the existing axle hub and its wheel mounting apparatus.